The human spine provides a vast array of functions, many of which are mechanical in nature. The spine is constructed to allow nerves from the brain to pass to various portions of the middle and lower body. These nerves, typically called the spinal cord, are located in a region within the spine called the spinal canal. Various nerve bundles emerge from the spine at different locations along the lateral length of the spine. In a healthy spine, these nerves are protected from damage and/or undue pressure thereon by the structure of the spine itself.
The spine has a complex curvature made up of a plurality of individual vertebrae (typically twenty-four) separated by intervertebral discs. The intervertebral discs hold the vertebrae together in a flexible manner so as to allow relative movement between the vertebrae from front to back and from side to side. This movement allows the body to bend forward and backward, to bend from side to side, and to rotate about a vertical axis. When the spine is operating properly, the nerves are maintained clear of the hard structure of the spine throughout the available ranges of motion.
Over time or because of accidents or disease, the intervertebral discs may lose height or become cracked, dehydrated, or herniated. The result is that the height of one or more discs may be reduced. The reduction in height can lead to compression of the nerve bundles. Such compression may cause pain and, in some cases, damage to the nerves.
Currently, there are many systems and methods at the disposal of a physician for reducing or eliminating the pain by minimizing the stress on the nerve bundles. In some instances, the existing disc is removed and an artificial disc is substituted therefore. In other instances, two or more vertebrae are fused together to prevent relative movement between the fused discs.
In some procedures, minimally invasive surgical procedures have been developed to fuse or otherwise treat vertebrae. Such procedures can reduce pain, post-operative recovery time, and the destruction of healthy tissue. Minimally invasive surgical procedures are particularly desirable for spinal and neurosurgical applications because of the need for access to locations deep within the body and the possible range of damage to vital intervening tissues.
Generally, it is desirable to access the surgical site using minimally invasive techniques or portals, rather than through a significant incision, to aid in preserving the integrity of the intervening tissues. In such procedures, however, it may be necessary to hold the edges of an incision apart to provide a clear operating field within which the surgeon can operate.
What is needed, therefore, is a tool or retractor adapted to work with minimally invasive procedures that allows the surgeon to have a clear path to the operating field, and a method for using such a tool or retractor.